Assessment of Exercise Intolerance in Patients with Pre-Dialysis CKD with Cardiopulmonary Function Testing: Translation to Everyday Practice

Abstract

<b><i>Background:</i></b> Chronic kidney disease (CKD) is often characterized by increased prevalence of cardiovascular risk factors and increased incidence of cardiovascular events and death. Reduced cardiovascular reserve and exercise intolerance are common in patients with CKD and are associated with adverse outcomes. <b><i>Summary:</i></b> The gold standard for identifying exercise limitation is cardiopulmonary exercise testing (CPET). CPET provides an integrative evaluation of cardiovascular, pulmonary, hematopoietic, neuropsychological, and metabolic function during maximal or submaximal exercise. It is useful in clinical setting for differentiation of the causes of exercise intolerance, risk stratification, and assessment of response to relevant treatments. A number of recent studies have used CPET in patients with pre-dialysis CKD, aiming to assess the cardiovascular reserve of these individuals, as well as the effect of interventions such as exercise training programs on their functional capacity. This review provides an in-depth description of CPET methodology and an overview of studies that utilized CPET technology to assess cardiovascular reserve in patients with pre-dialysis CKD. <b><i>Key Messages:</i></b> CPET can delineate multisystem changes and offer comprehensive phenotyping of factors determining overall cardiovascular risk. Potential clinical applications of CPET in CKD patients range from objective diagnosis of exercise intolerance to preoperative and long-term risk stratification and providing intermediate endpoints for clinical trials. Future studies should delineate the association of CPET indexes, with cardiovascular and respiratory alterations and hard outcomes in CKD patients, to enhance its diagnostic and prognostic utility in this population.

Different Interdialytic Intervals and Cardiorespiratory Fitness in Patients Undergoing Hemodialysis

“…37,38 CPET provides an integrative assessment of the cardiovascular, pulmonary, muscular, and neuropsychologic responses during exercise, allowing the assessment of the physiologic reserves of these systems. 14,22 Thus, CPET is the gold standard for evaluating causes of exercise intolerance, especially in patients with cardiovascular or respiratory disorders. Several studies aimed to evaluate cardiorespiratory fitness of CKD patients using the CPET technology 13 and clearly suggest that VO 2 peak and VO 2 anaerobic threshold are lower in patients with CKD compared with non-CKD counterparts 12 and are further deteriorating with advancing CKD stages.…”

“…Peak oxygen uptake (VO 2 peak) is probably the most important physiologic parameter measured with CPET, reflecting an individual's capacity to take in, transport, and use oxygen. 14,15…”

“…11,12 Pathogenesis of exercise intolerance in kidney failure is multifactorial, including cardiac/vascular dysfunction, morphological and functional abnormalities of skeletal muscles, nervous system impairment, anemia, and other uremia-related mechanisms that affect muscle oxygen utilization. 13,14 Cardiopulmonary exercise testing (CPET) is the gold standard method for evaluating cardiorespiratory fitness; it allows examination of cardiorespiratory and metabolic responses during exercise, providing information on exercise capacity, gas exchange, ventilator efficacy, and cardiac function. Peak oxygen uptake (VO 2 peak) is probably the most important physiologic parameter measured with CPET, reflecting an individual's capacity to take in, transport, and use oxygen.…”

“…Peak oxygen uptake (VO 2 peak) is probably the most important physiologic parameter measured with CPET, reflecting an individual's capacity to take in, transport, and use oxygen. 14,15 Although numerous studies have used CPET methodology to evaluate issues relevant to cardiorespiratory fitness in CKD, kidney failure, or postkidney transplantation, 12,16,17 no study so far has investigated the effects of the 3-day interdialytic interval on cardiorespiratory fitness. Therefore, the aim of this study was to examine differences in CPET parameters between the end of the 2-day and the end of the 3day interval in hemodialysis.…”

Cardiorenal syndrome and the association with fitness: Data from a telerehabilitation randomized clinical trial

“…Reduced cardiorespiratory fitness in chronic kidney disease is well known, 3,17,18 and various mechanisms have been suggested. Volume overload and systemic venous congestion is a frequent problem in both CHF and CKD 19–21 .…”